cgroup_freezer: trivial cleanups

* Clean-up indentation and line-breaks.  Drop the invalid comment
  about freezer->lock.

* Make all internal functions take @freezer instead of both @cgroup
  and @freezer.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>